import javax.jnlp.ClipboardService;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: happyiu
 * Date: 2021-11-19
 * Time: 19:50
 */

class ListNode{
    public int val;
    public ListNode prev;
    public ListNode next;

    public ListNode(int val) {
        this.val = val;
    }
}

public class MyListNode {
    public ListNode head;//指向双向链表的头节点
    //public ListNode head = new ListNode(-1);//指向双向链表的头节点
    public ListNode last;//指向的是尾巴节点

    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);//新增的头
        if(head == null){
            //如果头为空，则头节点尾节点都是该节点
            head = node;
            last = node;

        }

        else{
            //如果不为空
            node.next = head;//先拿头
            head.prev = node;//再拿新头
            head = node;//换新头
        }
    }

    //尾插法
    public void addLast(int data){

            ListNode node = new ListNode(data);
            if(this.head == null) {
                this.head = node;
                this.last = node;
            }else {
                this.last.next = node;
                node.prev = this.last;
                this.last = node;
            }
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        ListNode node = new ListNode(data);

        if(index < 0 || index > size()) {
            System.out.println("index位置不合法！");
            return;
        }

        if(index == 0){
             addFirst(data);
             return;
        }
        else if(index == size()){
            addLast(data);
            return;
        }
        else{
            ListNode cur = searchIndex(index);
      /*      cur.prev.next = node;
            node.prev = cur.prev;
            node.next = cur;
            cur.prev = node;*/

            node.next = cur.prev.next;
            cur.prev.next = node;
            node.prev = cur.prev;
            cur.prev = node;

        }

    }
    public ListNode searchIndex(int index){
        ListNode cur = head;
        while(index != 0){
            cur = cur.next;
            index--;
        }
        return cur;
    }



    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        if(head == null){
            return false;
        }
        ListNode cur = head;

        while (cur != null){
            if(cur.val == key){
                return true;
            }
                cur = cur.next;

        }
        return false;


    }
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = this.head;
        while (cur != null) {
            if(cur.val == key) {
                if(cur == head) {
                    head = head.next;
                    if(head != null) {
                        head.prev = null;
                    }else {
                        last = null;
                    }
                }else {
                    cur.prev.next = cur.next;
                    if(cur.next != null) {
                        //中间位置
                        cur.next.prev = cur.prev;
                    }else {
                        last = last.prev;
                    }
                }
                return;
            }
            cur = cur.next;
        }
    }


    
    //删除所有值为key的节点
    public void removeAllKey(int key){

    }

    //得到单链表的长度
    public int size(){
        if(head == null){
            return -1;
        }
        ListNode cur = head;
        int count=0;

        while (cur != null){
            count++;
            cur = cur.next;
        }
      return count;

    }

    public void display(){
        if(head == null){
            return;
        }
        ListNode cur = head;

        while (cur != null){
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();

    }
    public void clear(){

        while(head != null){
           ListNode curNext = head.next;
           head.prev=null;
           head.next=null;
           head = curNext;
        }
        last = null;
    }




}
